With an increase in demand for portable mobile terminal equipment, batteries having a flat shape and a high energy density are required. For example, in order to increase efficiency in housing batteries into battery cases, a laminate as shown in FIG. 6 that includes a positive electrode, a negative electrode and a separator is proposed (see Patent Documents 1 and 2). The laminate 51 of FIG. 6 is formed by folding an electrode group 59 including a positive electrode 54, a negative electrode 57 and a separator 58 interposed therebetween in a zigzag pattern. The positive electrode 54 includes a positive electrode current collector 52 made of an aluminum foil, and a positive electrode active material layer 53 made of a lithium composite oxide, such as LiCoO2, which is carried on the positive electrode current collector 52. The negative electrode 57 includes a negative electrode current collector 55 made of a copper foil, and a negative electrode active material layer 56 made of a carbonaceous material which is carried on the negative electrode current collector 55.
In the battery described in Patent Document 1, a region carrying no active material is formed in at least one of the positive electrode current collector and the negative electrode current collector, and that region can be used as a bent portion of the laminate. In this case, because neither the positive electrode active material layer nor the negative electrode active material layer is present in the bent portion, the bent portion is thin. This allows the laminate to have a uniform thickness.
Also, a battery configured as shown in FIG. 7 is proposed (see Patent Document 3). In the battery of FIG. 7, a laminate 51 as shown in FIG. 6 is also used. An electrically insulating sealant 61 is arranged around the laminate 51. A conductive plate member 62 is disposed such that it is in contact with the positive electrode current collector 52 located on the undersurface of the laminate. The conductive plate member 62 serves as a positive electrode terminal. Similarly, a conductive plate member 63 is disposed such that it is in contact with the negative electrode current collector 55 located on the upper surface of the electrode group. The conductive plate member 63 serves as a negative electrode terminal.                Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 9-7610        Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 8-264206        Patent Document 3: Japanese Laid-Open Patent Publication No. Hei 6-140077        